==================================================================
BUG: KCSAN: data-race in __add_to_page_cache_locked / truncate_inode_pages_range

write to 0xffff88811eddcb40 of 8 bytes by task 15168 on cpu 0:
 __add_to_page_cache_locked+0x2cc/0x6e0 mm/filemap.c:867
 add_to_page_cache_lru+0xa0/0x1b0 mm/filemap.c:918
 page_cache_readahead_unbounded+0x234/0x440 mm/readahead.c:228
 ondemand_readahead+0x4e4/0x6e0 mm/readahead.c:273
 page_cache_async_readahead+0x1c6/0x1e0 mm/readahead.c:631
 generic_file_buffered_read+0x322/0x1800 mm/filemap.c:2041
 generic_file_read_iter+0x7d/0x3e0 mm/filemap.c:2307
 ext4_file_read_iter+0x2d6/0x420 fs/ext4/file.c:74
 call_read_iter include/linux/fs.h:1901 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 __vfs_read+0x2d5/0x330 fs/read_write.c:428
 vfs_read+0x131/0x2a0 fs/read_write.c:462
 ksys_read+0xce/0x180 fs/read_write.c:588
 __do_sys_read fs/read_write.c:598 [inline]
 __se_sys_read fs/read_write.c:596 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:596
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811eddcb40 of 8 bytes by task 15178 on cpu 1:
 truncate_inode_pages_range+0x40/0xf10 mm/truncate.c:303
 truncate_pagecache_range+0x80/0x90 mm/truncate.c:931
 ext4_punch_hole+0x371/0xa20 fs/ext4/inode.c:4031
 ext4_fallocate+0xe5/0x560 fs/ext4/extents.c:4659
 vfs_fallocate+0x431/0x580 fs/open.c:309
 madvise_remove mm/madvise.c:857 [inline]
 madvise_vma mm/madvise.c:940 [inline]
 do_madvise+0x83d/0x14e0 mm/madvise.c:1145
 __do_sys_madvise mm/madvise.c:1171 [inline]
 __se_sys_madvise mm/madvise.c:1169 [inline]
 __x64_sys_madvise+0x3e/0x50 mm/madvise.c:1169
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15178 Comm: syz-executor.0 Not tainted 5.8.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================